Usnea species are classified as fruticose lichens, which are a symbiosis of fungus and algae. Usnea grows on the bark and wood of coniferous (e.g., spruces, firs, and pines) and deciduous hardwood (e.g., oak, hickory, walnut, apple, and other fruit trees) host trees throughout the northern hemisphere in Asia, Europe, and North America.

Usnea has been used as a therapeutic agent in traditional Chinese medicine (TCM) for thousands of years. Usnea longissima is traditionally taken by mouth for lung and upper respiratory infections, and applied on the skin to treat surface infections or external ulcers. It is still used today in TCM in liquid extract and tincture form to treat tuberculosis lymphadenitis.

Usnic acid is a secondary metabolite uniquely found in all lichens. Usnea or usnic acid has been used as a human papillomavirus (HPV) treatment and as an oral hygiene agent, with limited effectiveness.

Usnic acid is also found in various oral (by mouth) dietary supplements, including Lipokinetix®, marketed as a weight loss agent. However, Lipokinetix® may not be safe and may cause liver damage. Lipokinetix®, now withdrawn from the market, contained phenylpropanolamine (PPA), caffeine, yohimbine hydrochloride, diiodothyronine and usnic acid.

These uses have been tested in humans or animals. Safety and effectiveness have not always been proven. Some of these conditions are potentially serious, and should be evaluated by a qualified healthcare provider.

GRADE *

Usnea and usnic acid both are reported in laboratory studies to have antiviral activity. A combination of usnic acid and zinc sulfate may help treat human papillomavirus. Additional study of usnea alone, and not in combination, is needed to a make a strong recommendation.

C

Usnea has been used historically as an oral antibacterial agent, and animal and laboratory studies support this. However, there is currently insufficient available evidence to recommend for or against the use of mouthwashes or rinses containing usnea extracts or usnic acid for oral hygiene.

C

* Key to grades

A: Strong scientific evidence for this useB: Good scientific evidence for this useC: Unclear scientific evidence for this useD: Fair scientific evidence for this use (it may not work)F: Strong scientific evidence against this use (it likley does not work)

Tradition / Theory
The below uses are based on tradition, scientific theories, or limited research. They often have not been thoroughly tested in humans, and safety and effectiveness have not always been proven. Some of these conditions are potentially serious, and should be evaluated by a qualified healthcare provider. There may be other proposed uses that are not listed below.

There is no proven safe or effective dose. However, the German Commission E has approved 1 usnea lozenge (equivalent of 100 milligrams powdered usnea lichen) 3-6 times daily for mouth irritation. Usnea has also been taken by mouth as a powder (100 milligrams three times a day), tea, or tincture (3-4 milliliters three times daily). Usnea has also been applied on the affected area(s) of the skin two or three times daily.

Children (younger than 18 years):

There is no proven safe or effective dose for usnea in children, and use is not recommended.

Safety
The U.S. Food and Drug Administration does not strictly regulate herbs and supplements. There is no guarantee of strength, purity or safety of products, and effects may vary. You should always read product labels. If you have a medical condition, or are taking other drugs, herbs, or supplements, you should speak with a qualified healthcare provider before starting a new therapy. Consult a healthcare provider immediately if you experience side effects.

Allergies

Avoid in individuals with a known allergy or hypersensitivity to usnea, its constituents, or related lichens. Usnea and its constituents have been reported to cause allergic reactions, such as skin rash, in individuals handling usnea, or using usnic acid vaginally. Deodorant sprays containing usnic acid have been linked to allergic contact eczema.

Side Effects and Warnings

It appears that usnea is not well tolerated in humans except when applied on the skin or used as a homeopathic agent. The chemical constituent usnic acid has been reported in laboratory studies to be toxic, and dietary supplement products containing usnic acid have been reported to cause liver damage. Based on available research, only preparations of homeopathic usnea are recommended for oral (taken by mouth) use at this time.

Usnea and usnic acid may cause contact dermatitis that may lead a hypersensitivity reaction, including urticaria ("hives"), rhinitis (runny or congested nose), asthma, or photoallergic contact dermatitis.

Although not well studied in humans, usnic acid may increase the risk of bleeding. Caution is advised in patients with bleeding disorders or taking drugs that may increase the risk of bleeding. Dosing adjustments may be necessary.

Pregnancy and Breastfeeding

Usnea or usnic acid is not recommended in pregnant or breastfeeding women based on a lack of available scientific evidence.

Usnea may increase bleeding time by inhibition of platelet aggregation. Caution is advised in patients with bleeding disorders or taking drugs that may increase the risk of bleeding. Some examples of drugs that increase the risk of bleeding include aspirin, anticoagulants (blood thinners) such as warfarin (Coumadin®) or heparin, anti-platelet drugs such as clopidogrel (Plavix ®), and non-steroidal anti-inflammatory drugs such as ibuprofen (Motrin®, Advil®) or naproxen (Naprosyn®, Aleve®). Dosing adjustments may be necessary.

Usnea may interfere with the way the body processes certain drugs using the liver's "cytochrome P450" enzyme system. As a result, the levels of these drugs may be decreased in the blood, and reduce the intended effects. Patients taking any medications should check the package insert and speak with a qualified healthcare professional, including a pharmacist, about possible interactions.

Interactions with Herbs and Dietary Supplements

Usnea may increase the risk of bleeding when taken with herbs and supplements that are believed to increase the risk of bleeding. Multiple cases of bleeding have been reported with the use of Ginkgo biloba, and fewer cases with garlic and saw palmetto. Numerous other agents may theoretically increase the risk of bleeding, although this has not been proven in most cases.

Usnea may interfere with the way the body processes certain herbs or supplements using the liver's "cytochrome P450" enzyme system. As a result, the levels of other herbs or supplements may become too low in the blood. It may also alter the effects that other herbs or supplements potentially may have on the P450 system.

The information in this monograph is intended for informational purposes only, and is meant to help users better understand health concerns. Information is based on review of scientific research data, historical practice patterns, and clinical experience. This information should not be interpreted as specific medical advice. Users should consult with a qualified healthcare provider for specific questions regarding therapies, diagnosis and/or health conditions, prior to making therapeutic decisions.